1. Field of the Invention
The present invention relates to an ultrasound diagnostic apparatus, an ultrasound diagnostic method, and a computer-readable storage medium for generating a tomographic image of a subject by transmitting and receiving ultrasound waves.
2. Description of the Related Art
An ultrasound diagnostic apparatus has been known that transmits an ultrasound wave to a subject from an ultrasound probe and generates a tomographic image of the subject based on a reflected wave from the inside of the subject. In such an ultrasound diagnostic apparatus, it is known that the propagation speed (also referred to as sound speed) of an ultrasound wave propagating through the subject is calculated and this is used in the diagnosis of tissue characteristics (lesions, hardness, and the like) in the subject.
For example, JP2004-97537A discloses an ultrasound diagnostic apparatus configured to calculate a sound speed value in a part of a subject corresponding to a set region of interest, as a tissue characteristic value, based on a reception signal from the inside of the subject and to output information regarding the history of the tissue characteristic value to a monitor.
In addition, JP1989-121039A (JP-H01-121039A) discloses an ultrasound diagnostic apparatus configured to calculate a sound speed value in a subject based on the propagation time from transmission to reception of an ultrasound wave propagating through the subject and to display the calculated sound speed value as the tissue characteristics information of the subject together with an ultrasound tomographic image.